Location: Helsinki, Finland
Known as Temppeliaukio Church (The Rock Church), this massive church is built directly into the bedrock in downtown Helsinki.
Completed in 1969, this underground house of worship was built by brothers Timo and Tuomo Suomalainen in the Toolo neighborhood. Despite the cave like atmosphere, this church actually has incredible acoustics in this 2 story parish. Fit with a built in organ, and seating for about 500, this is truly an incredible architecture feat.